Stirrup



FIG. 1 is a front elevational view of a stirrup showing my new design, with the rear view being identical;

FIG. 2 is a right side elevational view thereof, the other side being identical;

FIG. 3 is a top plan view thereof; and,

FIG. 4 is a bottom plan view thereof. 

The ornamental design for a stirrup, as shown and described. 